/**

 *

 * Secure Hash Algorithm (SHA256)

 * http://www.webtoolkit.info/

 *

 * Original code by Angel Marin, Paul Johnston.

 *

 **/

export function SHA256(s) {
  var chrsz = 8

  var hexcase = 0

  function safe_add(x, y) {
    var lsw = (x & 0xffff) + (y & 0xffff)

    var msw = (x >> 16) + (y >> 16) + (lsw >> 16)

    return (msw << 16) | (lsw & 0xffff)
  }

  function S(X, n) {
    return (X >>> n) | (X << (32 - n))
  }

  function R(X, n) {
    return X >>> n
  }

  function Ch(x, y, z) {
    return (x & y) ^ (~x & z)
  }

  function Maj(x, y, z) {
    return (x & y) ^ (x & z) ^ (y & z)
  }

  function Sigma0256(x) {
    return S(x, 2) ^ S(x, 13) ^ S(x, 22)
  }

  function Sigma1256(x) {
    return S(x, 6) ^ S(x, 11) ^ S(x, 25)
  }

  function Gamma0256(x) {
    return S(x, 7) ^ S(x, 18) ^ R(x, 3)
  }

  function Gamma1256(x) {
    return S(x, 17) ^ S(x, 19) ^ R(x, 10)
  }

  function core_sha256(m, l) {
    var K = new Array(
      0x428a2f98,
      0x71374491,
      0xb5c0fbcf,
      0xe9b5dba5,
      0x3956c25b,
      0x59f111f1,
      0x923f82a4,
      0xab1c5ed5,
      0xd807aa98,
      0x12835b01,
      0x243185be,
      0x550c7dc3,
      0x72be5d74,
      0x80deb1fe,
      0x9bdc06a7,
      0xc19bf174,
      0xe49b69c1,
      0xefbe4786,
      0xfc19dc6,
      0x240ca1cc,
      0x2de92c6f,
      0x4a7484aa,
      0x5cb0a9dc,
      0x76f988da,
      0x983e5152,
      0xa831c66d,
      0xb00327c8,
      0xbf597fc7,
      0xc6e00bf3,
      0xd5a79147,
      0x6ca6351,
      0x14292967,
      0x27b70a85,
      0x2e1b2138,
      0x4d2c6dfc,
      0x53380d13,
      0x650a7354,
      0x766a0abb,
      0x81c2c92e,
      0x92722c85,
      0xa2bfe8a1,
      0xa81a664b,
      0xc24b8b70,
      0xc76c51a3,
      0xd192e819,
      0xd6990624,
      0xf40e3585,
      0x106aa070,
      0x19a4c116,
      0x1e376c08,
      0x2748774c,
      0x34b0bcb5,
      0x391c0cb3,
      0x4ed8aa4a,
      0x5b9cca4f,
      0x682e6ff3,
      0x748f82ee,
      0x78a5636f,
      0x84c87814,
      0x8cc70208,
      0x90befffa,
      0xa4506ceb,
      0xbef9a3f7,
      0xc67178f2
    )

    var HASH = new Array(
      0x6a09e667,
      0xbb67ae85,
      0x3c6ef372,
      0xa54ff53a,
      0x510e527f,
      0x9b05688c,
      0x1f83d9ab,
      0x5be0cd19
    )

    var W = new Array(64)

    var a, b, c, d, e, f, g, h, i, j

    var T1, T2

    m[l >> 5] |= 0x80 << (24 - (l % 32))

    m[(((l + 64) >> 9) << 4) + 15] = l

    for (var i = 0; i < m.length; i += 16) {
      a = HASH[0]

      b = HASH[1]

      c = HASH[2]

      d = HASH[3]

      e = HASH[4]

      f = HASH[5]

      g = HASH[6]

      h = HASH[7]

      for (var j = 0; j < 64; j++) {
        if (j < 16) W[j] = m[j + i]
        else {
          W[j] = safe_add(
            safe_add(
              safe_add(Gamma1256(W[j - 2]), W[j - 7]),
              Gamma0256(W[j - 15])
            ),
            W[j - 16]
          )
        }

        T1 = safe_add(
          safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]),
          W[j]
        )

        T2 = safe_add(Sigma0256(a), Maj(a, b, c))

        h = g

        g = f

        f = e

        e = safe_add(d, T1)

        d = c

        c = b

        b = a

        a = safe_add(T1, T2)
      }

      HASH[0] = safe_add(a, HASH[0])

      HASH[1] = safe_add(b, HASH[1])

      HASH[2] = safe_add(c, HASH[2])

      HASH[3] = safe_add(d, HASH[3])

      HASH[4] = safe_add(e, HASH[4])

      HASH[5] = safe_add(f, HASH[5])

      HASH[6] = safe_add(g, HASH[6])

      HASH[7] = safe_add(h, HASH[7])
    }

    return HASH
  }

  function str2binb(str) {
    var bin = Array()

    var mask = (1 << chrsz) - 1

    for (var i = 0; i < str.length * chrsz; i += chrsz) {
      bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - (i % 32))
    }

    return bin
  }

  function Utf8Encode(string) {
    string = string.replace(/\r\n/g, '\n')

    var utftext = ''

    for (var n = 0; n < string.length; n++) {
      var c = string.charCodeAt(n)

      if (c < 128) {
        utftext += String.fromCharCode(c)
      } else if (c > 127 && c < 2048) {
        utftext += String.fromCharCode((c >> 6) | 192)

        utftext += String.fromCharCode((c & 63) | 128)
      } else {
        utftext += String.fromCharCode((c >> 12) | 224)

        utftext += String.fromCharCode(((c >> 6) & 63) | 128)

        utftext += String.fromCharCode((c & 63) | 128)
      }
    }

    return utftext
  }

  function binb2hex(binarray) {
    var hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef'

    var str = ''

    for (var i = 0; i < binarray.length * 4; i++) {
      str +=
        hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8 + 4)) & 0xf) +
        hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8)) & 0xf)
    }

    return str
  }

  s = Utf8Encode(s)

  return binb2hex(core_sha256(str2binb(s), s.length * chrsz))
}
